Overhaul of docs

[alexgubanow]

1. Basic documentation
Ensure user-facing documentation clearly explains:

• How to install the software (Java and C++)
• How to start/run it
• How to use it (with concrete examples)
• How to use it securely (brief guidance on untrusted input, resource usage, binary mode, privileges)

Primary location: README.md
Additional docs may be linked if needed.

2. External interface documentation

Provide reference documentation for all external interfaces:

CLI reference:

• command synopsis
• supported options/flags
• parameters (input/output)
• example invocations

C++ API reference (libtersedecompress.a):

• public headers
• main functions/classes
• usage notes and error behavior

Java API reference:

• public entry points and usage notes

3. Release & support documentation references

Ensure README links to:

• RELEASE.md (release process and cadence)
• SUPPORT.md (how users get help and report issues)

4. Development process transparency

Add a short note (e.g., in RELEASE.md or CONTRIBUTING.md) clarifying:

• Development happens continuously in the public repository
• Commits and PRs occur between releases
• Release tags represent stable snapshots, not the only history

5. FLOSS build tooling statement

Add a short statement confirming the project can be built using only FLOSS tools:

• Java: OpenJDK + Maven
• C++: open-source compiler + make/cmake